High temperature combustion systems, such as gas turbines, or gasifiers used for the gasification of coal, petroleum coke, biomass, oil refinery bottoms, or the like, generally involve reactions at temperatures in the range of about 700° C. to about 2,500° C., and under pressures as high as 100 atmospheres. Under these conditions, components in the combustion systems are exposed to reducing environments, corrosive gases and condensing acids, and are subject to attack by slag, ash, char, thermal shock, or the like, which leads to failure of the components, or of the combustion system itself.
Some of the problems associated with high temperature combustion systems is attack by and/or build up of slag, ash, char, or the like, on the surfaces of vulnerable components, that is, components which are prone to the foregoing. Slag, for example, is highly reactive with metals and ceramics. Metal components, such as metal feed injectors designed for high temperature gasification processes, suffer from corrosive attack by slag, or by oxygen, sulfur, or the like. Ceramic components, such as ceramic feed injectors, nozzle components, shields, or inserts, also suffer from a similar attack. In addition, poor mechanical attachment between different components, specifically between ceramic components and metal components, tends to lead to mechanical failure of the components, generally due to thermal shock. Component failure leads to, collateral component damage, disadvantageous plant downtime, decreased reliability over service life, and costly repair or replacement, among others. Thermal shock occurs due to rapid increase or decrease in operating temperatures. Components susceptible to thermal shock, such as nozzles, generally require the inclusion of complex mechanisms, such as active water cooling, to mitigate failure due to thermal shock.
Therefore, there exists a need for high temperature combustion systems and components thereof that are highly resistant to chemical attack by slag, thermal shock and fatigue, acid corrosion, reducing environments, and the like. Such a system can operate under high thermal gradients without the further risk of mechanical, failure. Also, the system should be resistant to fouling due to the deposition of slag, ash, or char.